Cell surface glycopeptides from retinoid-treated more adhesive and control mouse fibroblasts 3T12 cells were analyzed. The biosynthesis of a major cell surface glycopeptide I of approximate MW 2100 was shown to be enhanced specifically by retinoic acid. This glycopeptide was characterized as belonging to the "complex" type by treatment with exo and endoglycosidases and by chromatography on Con A Sepharose. Glycopeptide I was a minor component of the total cellular glycopeptides which contained mostly glycopeptide II of approximate molecular weight 1500. This glycopeptide was shown to be of the "polymannose" type. Retinoic acid also increased the number of receptor sites for epidermal growth factor (EGF) by six to ten fold. This effect was specific for retinoids with biological activity in other systems. Inasmuch as EGF-receptors are glycoproteins, it is suggested that the effect of retinoic acid on 3T12 cells may well be the result of its action on cell surface glycoproteins.